The desire to reduce the cost and increase the ease and speed of refuse collection, in conjunction with improvements in automation techniques, has resulted in substantial changes in the collection of residential and commercial refuse. Most modern refuse collection systems include carts having wheels, which allow them to be rolled to the street curb, where they are lifted and dumped by a semi- or fully automated lift mechanism.
In conjunction with the trend toward increased efficiency there is a desire to improve the recycling of waste materials. To improve the collection process for recyclable waste, customers are being provided with separate containers for different wastes, or with refuse carts which are capable of segregating either two or more types of refuse, namely, recyclable and nonrecyclable waste or two or more different types of recyclable refuse, such as paper and plastic, examples of such containers may be seen in U.S. Pat. Nos. 4,715,767, 4,113,125 and Des. 343,490.
The use of divided refuse carts requires the corresponding refuse collection vehicle to be provided with a collection hopper which is divided into separate chambers. Advantageously, the separate chambers are designed for use with divided refuse carts so that the contents of the divided refuse cart fall into the proper chamber upon emptying of the cart into the vehicle. In such instances, the divided cart is lifted and emptied so that the refuse cart is accurately aligned above the truck, to ensure that the contents of the compartmentalized cart fall into the proper chamber in the truck so as to avoid cross-contamination.
Several problems have developed as a consequence of providing a divided collection hopper to receive two different types of refuse. One of the more common problems relates to compacting and retaining the waste within the separate chambers. Because of the different nature and characteristics of the refuse being collected within each of the chambers, different methods must be used to adequately compact and retain the refuse. For instance, the compacting pressure required to overcome plastic's tendency to retain its shape after it has been compacted is higher than the compacting pressure required to crush glass. As a result, when plastic and glass are placed into the same collection chamber, unless the plastic is adequately compressed, it will bubble or spill over the advancing packer blade into the other chamber, thereby contaminating the contents of the other chamber. However, sufficiently compacting the plastic to overcome its tendency to retain its shape results in crushing the glass received within the same chamber. Crushing the glass significantly reduces its ability to be recycled. An example of existing approaches which have not overcome this problem may be seen in U.S. Pat. Nos. 5,288,196 and 5,316,430 to Horning et al. These patents disclose a refuse truck having a packer or blade reciprocatingly located in respective upper and lower compartments.
An alternative approach was developed by the applicant in its prototype truck for the City of Visalia, Calif. This approach relied on a pair of separately driven packers, one for each the upper and lower compartments of the truck, cooperating through a pressure sequence valve, with a separately driven bucket and a separately driven blade. This prototype was cost prohibitive; therefore, Applicant subsequently developed a twin packer or compactor ram prototype which used a single actuator to drive a lower packer which was connected to and drove a similarly shaped upper packer. Applicant however found this second prototype to suffer various inadequacies.
Based on the inability of current technology to adequately retain the plastic without damaging the glass contained within the same chamber, collection companies are forced to choose among unsatisfactory alternatives of contamination of non-plastic refuse by the plastic spilling over the packer into the second chamber, or crushing glass refuse when plastic and paper are collected together in the same chamber. None of these alternatives fulfills the objective for separating the refuse collected in a cost effective manner.
A second problem with using a divided collection hopper is that the refuse truck can only remain on its route until one of the chambers is filled. Consequently, depending on the day of the week and the nature of the refuse to be collected, the refuse collection vehicle may be forced to make several trips to the landfill or to the recycling center to unload the full chamber while the other chamber remains relatively empty. In such situations, the use of a divided hopper not only increases the cost but also results in great inefficiency in the collection system. This is especially true on collection days when a recyclable collection is being made. Frequently the collection chamber receiving paper products, such as newspapers, will fill much more quickly than the chamber receiving the plastic and glass. As a result, efforts have been made to vary the size of the respective chambers within the hopper as collection routes or the types of refuse being collected change.
One approach to solve this problem is set forth in U.S. Pat. No. 5,122,025 to Glomski which discloses a refuse collection truck having a divided collection hopper. A dividing wall separating the two chambers is adjustable along parallel tracks to move the dividing wall to vary the relative size of the compartments. Movement of the divider wall is manually controlled by the operator. This approach however requires separate openings for each of the compartments, thereby requiring refuse to be separately dumped into each compartment at different locations along the hopper.
A third problem arises once the refuse has been collected within the divided hopper. One of the reasons for separating the refuse in a divided hopper is to be able to dump the separated refuse in different locations within a recycling center or a transfer station or other locations dedicated to different types of refuse. Therefore, it is necessary to be able to separately empty each of the chambers. Several different approaches to separately emptying the divided collection hopper have developed. For example U.S. Pat. No. 5,122,025 to Glomski discloses a refuse collection vehicle which requires a divider wall separating the chambers to be locked to allow separate emptying of one chamber while retaining the material in the second chamber. In this configuration, the refuse to be emptied first must always be loaded into the rearward chamber. U.S. Pat. No. 5,316,430 to Horning et al. discloses a refuse collection vehicle having a tailgate with separate, independently operating discharge doors. The doors must be manually opened and closed to separately discharge refuse from either of the chambers. Similarly, U.S. Pat. No. 5,288,196 to Horning et al. discloses a refuse collection vehicle having a set of discharge doors wherein an inner discharge door overlays one chamber and a larger outer door overlies both chambers. To empty the upper chamber requires opening the outer door while the closed inner door retains the refuse in the lower chamber. To empty the lower chamber requires opening both the inner and the outer doors.
Based on the approaches currently available, collection companies are forced to either load the recyclables into various compartments in the order in which they are to be discharged, manually open and close separate discharge doors or open two doors to separately dump the contents of the collection chambers.